Vehicle seat

ABSTRACT

The object of the invention is to provide a vehicle seat which can improve degree of freedom in the design of the vehicle seat. A vehicle seat with a seat cushion and a seat back includes: right and left side frames 20 constituting right and left frames of the seat back; a pressure-receiving member 40 disposed between the right and left side frames 20 and configured to receive a load from an occupant; and a driving mechanism 50 disposed at each of right and left sides of the pressure-receiving member 40 and configured to cause a right end portion or a left end portion of the pressure-receiving member 40 to move from an initial position to an advanced position that is located frontward of the initial position or to move from the advanced position to the initial position, wherein the driving mechanism 50 includes a linkage (drive link member 100 and contact link member 200) configured to be connected to the pressure-receiving member 40 and a driving source 52 configured to actuate the linkage, and wherein the linkage is configured to operate when a load equal to or greater than a predetermined amount is input from the occupant to the pressure-receiving member 40 to cause the pressure-receiving member 40 to move to a backward position that is located rearward of the initial position.

TECHNICAL FIELD

The present invention relates to a vehicle seat with a seat cushion anda seat back.

BACKGROUND ART

Conventionally, there is known a vehicle seat for a car and the like, inwhich a part of a seat back is oriented to a turning direction so that acentrifugal force applied to an occupant during cornering isappropriately supported by the seat back (see patent Documents 1-3).

For example, a seat described in Patent Document 1 comprises right andleft side frames of a seat back, a long link member disposed between theright and left side frames and configured to support an occupant througha movable cushion, and a short link member rotatably provided at eachside frame and connected to each side of the long link member, whereinthe orientation of the movable cushion is changed by actuating the link.

A seat device described in Patent Document 2 comprises a back platedisposed between right and left side frames of a seat back and havingswingable end portions configured to be movable frontward and rearwardrelative to the right and left side frames, a link member configured tobe rotatable frontward and rearward relative to the right and left sideframes and to cause a swinging motion of the back plate, and a drivingsource for rotating the link member, wherein the back plate is orientedtoward a turning direction of the vehicle by rotating the link member.

Further, there is known a vehicle seat comprising a pressure-receivingmember disposed between right and left side frames and configured toreceive a load from an occupant, wherein when the car is rear-ended byanother car or when the car collides at the rear portion thereof withanother car or a structural object while reversing (i.e., rear-endcollision), a load from the occupant causes the pressure-receivingmember to move rearward so that the upper body of the occupant can sinkinto a seat back (see Patent Document 3). With this configuration, thehead of the occupant quickly approaches to a headrest and thus getssupported by the headrest, so that an impact imparted to the neck of theoccupant due to the rear-end collision can be reduced.

CITATION LIST Patent Literature

Patent Document 1: JP4569293 B2

Patent Document 2: JP2013-49356 A

Patent Document 3: JP2012-136063 A

SUMMARY OF THE INVENTION

However, if the function of appropriately supporting an occupant duringcornering and the function of reducing an impact in the rear-endcollision are both realized in a conventional vehicle seat, it isnecessary that the vehicle seat has to include a mechanism for changingthe oriention of a part of the seat back as well as a mechanism forallowing a rearward movement of the pressure-receiving member. Thesemechanisms may disadvantageously occupy a large space within the seatback, which makes it difficult to arrange other mechanisms or to reducethe size of the seat; as a result, there is a possibility to limit thedegree of freedom in the design of the vehicle seat.

Further, it is desirable that in the vehicle seat, a movable member(e.g., back plate) to be movable relative to a frame and a link memberto be rotatable relative to the frame are smoothly operated.

In the conventional art, it is difficult to precisely regulate theamount of rotation of the link member because the amount of rotation ofthe link member (inclination of the back plate) is regulated bycontrolling actuation and stoppage of the driving source.

Further, it is necessary that various parts such as the link member andthe driving source are arranged in limited space of the vehicle seatwhile suppressing increase in size of the vehicle seat. Therefore, acompact structure is desirable for these parts themselves and peripheralspace of these parts.

In view of the above background, it is an object of the presentinvention to provide a vehicle seat which can improve the degree offreedom in design.

Also, it is an object of the present invention to provide a vehicle seatin which the link member and the movable member are smoothly operated.

Also, it is an object of the present invention to provide a vehicle seatwhich can precisely regulate the amount of rotation of the link member.

Also, it is an object of the present invention to provide a vehicle seatin which the size of the driving source and the structure around thedriving source can be downsized.

The present invention proposed to attain one or more of the aboveobjects provides a vehicle seat with a seat cushion and a seat back, thevehicle seat comprising: right and left side frames constituting rightand left frames of the seat back; a pressure-receiving member disposedbetween the right and left side frames and configured to receive a loadfrom an occupant; and a driving mechanism disposed at each of right andleft sides of the pressure-receiving member and configured to cause aright end portion or a left end portion of the pressure-receiving memberto move from an initial position to an advanced position that is locatedfrontward of the initial position or to move from the advanced positionto the initial position, wherein the driving mechanism comprises alinkage configured to be connected to the pressure-receiving member anda driving source configured to actuate the linkage, and wherein thelinkage is configured to operate when a load equal to or greater than apredetermined amount is input from the occupant to thepressure-receiving member to cause the pressure-receiving member to moveto a backward position that is located rearward of the initial position.

With this configuration, the driving mechanism can provide a function ofappropriately supporting an occupant by causing the right end portion orthe left end portion of the pressure-receiving member to move frontwardand rearward during cornering as well as a function of reducing animpact imparted to the neck of the occupant by moving thepressure-receiving member to the backward position in a rear-endcollision. This makes it unnecessary to provide within the seat backboth the mechanism for changing the orientation of the seat back and themechanism for allowing a rearward movement of the pressure-receivingmember, so that space within the seat back can be ensured to arrangeother mechanisms or the seat can be downsized; it is therefore possibleto improve the degree of freedom in the design of the vehicle seat.

In the above vehicle seat, the linkage may include a link memberconfigured to be rotatable frontward and rearward relative to the sideframe and connected to the pressure-receiving member, and the vehicleseat may comprise a rotation resistive member configured to restrict arearward rotation of the link member when a load smaller than thepredetermined amount is input from the occupant to thepressure-receiving member and to deform when a load equal to or greaterthan the predetermined amount is input from the occupant to thepressure-receiving member so as to allow a rearward rotation of the linkmember.

This configuration can prevent the pressure-receiving member from movingto the backward position when the vehicle is in a normal conditionwithout undergoing a rear-end collision.

In the above vehicle seat, the rotation resistive member may comprise aconnecting wire configured to connect the pressure-receiving member andthe link member.

Further, in the above vehicle seat, the rotation resistive member maycomprise an urging member configured to urge the link member to rotatefrontward.

In the above vehicle seat, the linkage may include a second link memberconnected to an output shaft of the driving source, and the link membermay be rotatable relative to the second link member.

With this configuration, as compared with the configuration in which onelink member is used to move the pressure-receiving member between theinitial position and the advanced position, a sufficient moving distanceof the pressure-receiving member is ensured with the result that thepressure-receiving member can favorably support the occupant duringcornering.

Further, in the above vehicle seat, the linkage may include a linkmember configured to be rotatable relative to the side frame to actuatethe pressure-receiving member; the link member may have a contactportion configured to contact the pressure-receiving member when thepressure-receiving member is caused to move, and as viewed from adirection of an axis of rotation of the link member, the contact portionmay have a convexly curved shape.

This configuration makes it possible to lessen the sliding resistancebetween the contact portion and the pressure-receiving member in therotating direction of the link member, so that the link member and thepressure-receiving member can be moved smoothly.

In the above vehicle seat, as viewed from a direction orthogonal to thedirection of the axis of rotation, the contact portion may have aconvexly curved shape.

This configuration makes it possible to lessen the sliding resistancebetween the contact portion and the pressure-receiving member also inthe rotating direction of the link member, so that the link member andthe pressure-receiving member can be moved smoothly.

In the above vehicle seat, the contact portion may have a sphericalshape.

This configuration makes it possible to lessen the sliding resistancebetween the contact portion and the pressure-receiving member in alldirections, so that the link member and the pressure-receiving membercan be moved smoothly.

In the above vehicle seat, the contact portion may be made of plasticresin.

With this configuration, rubbing noise generated between the link memberand the pressure-receiving member can be suppressed and the abrasion canbe suppressed.

In the above vehicle seat, the link member may comprise a link body, anda cover member provided with the contact portion and configured to coverat least a part of the link body.

With this configuration, each of the link body and the cover member canbe made of an optimum material in terms of its function.

Further, in the above vehicle seat, the linkage may include a secondlink member configured to be rotatable relative to the side frame and toactuate the pressure-receiving member; the driving source may beconfigured to rotate the second link member; the right-side second linkmember and the left-side second link member may be independentlyrotatable to each other; and the second link member may have a stopperportion configured to contact a corresponding side frame or a memberfixed relative to the corresponding side frame to restrict a rotation ofthe second link member.

With this configuration, since the stopper portion of the second linkmember contacts the side frame or the member fixed relative to the sideframe to restrict a rotation of the second link member, the amount ofrotation of the second link member can be precisely regulated ascompared with the configuration in which the amount of rotation thereofis regulated by controlling the driving source.

In the above vehicle seat, the stopper portion may comprise a firststopper portion configured to restrict a rotation of the second linkmember in one direction and a second stopper portion configured torestrict a rotation of the second link member in a direction opposite tothe one direction.

This configuration makes it possible to precisely regulate the amount ofrotation of the second link member both when the second link memberrotates in the one direction and when the second link member rotates inthe opposite direction.

In the above vehicle seat, the right-side second link member and theleft-side second link member each may be formed using a common part.

This configuration makes it possible to reduce the number of parts andto save the effort of parts management, so that reduction in the costcan be achieved. Further, the mix-up between right and left parts can beprevented and the assembling is facilitated.

In the above vehicle seat, the second link member may be shaped as aplate, and the stopper portion may be provided on a side surfacesurrounding an axis of rotation of the second link member.

With this configuration, the structure of the second link member can besimplified as compared with the configuration in which the stopperportion protrudes from the second link member in a direction of the axisof rotation, so that the second link member having the stopper portioncan be easily manufactured. Further, as compared with the configurationin which the stopper portion protrudes from the second link member onlyin one side in the direction of the axis of rotation, the right-sidesecond link member and the left-side second link member are easilydesigned to be a commonly applicable part.

The above vehicle seat may further comprise a bracket with which thedriving mechanism is fixed to the side frame; and a fixed stopper memberfixed relative to the side frame and configured such that a rotation ofthe second link member is restricted when the stopper portion contactsthe fixed stopper member, and the fixed stopper member may be fixed tothe bracket.

With this configuration, the positional precision between the secondlink member (stopper portion) of the driving mechanism and the fixedstopper member can be improved, so that the amount of rotation of thesecond link member can be more precisely regulated.

Further, in the above vehicle seat, the side frame may have a pair ofbent portions formed by bending laterally inward both side portionsthereof each located at an end in a width direction; the driving sourcemay comprise a motor, a gearbox configured to accommodate a train ofgears for reducing speed with which is transmitted a rotary drivingforce generated by the motor, and an output shaft configured to outputthe rotary driving force transmitted with the reduced speed; the gearboxmay have a fastening portion protruding radially outward of the outputshaft such that a fastening member for closing an axial end portion ofthe output shaft is disposed in the fastening portion; and as viewedfrom an axial direction of the output shaft, the fastening portion maybe arranged at a position avoiding a straight line connecting ends ofthe pair of bent portions.

With this configuration, side surfaces of the gearbox except for thefastening portion have recessed shapes with respect to the fasteningportion, so that the driving source with the gearbox can be compactlyformed. Further, the side surfaces of the gearbox except for thefastening portion and the end portions of the pair of bent portions ofthe side frame can be arranged closer to each other, so that upsizing ofthe side frame can be suppressed and the structure around the drivingsource can be downsized.

In the above vehicle seat, as viewed from the axial direction, thefastening portion may be provided at a plurality of positions, at leastone on each side of the straight line.

With this configuration, even if the vehicle seat comprises a pluralityof fastening portions, the side surfaces of the gearbox except for thefastening portions and the end portions of the pair of bent portions ofthe side frame can be arranged closer to each other, so that thestructure around the driving source can be downsized.

The above vehicle seat may further comprise a bracket with which thedriving source is fixed to the side frame, and the bracket may comprisean engagement portion engageable with one end portion of the drivingsource located at one end thereof in the axial direction of the drivingsource, and a fixing portion extending along the side frame from an endportion of the engagement portion located closer to the side frametoward a direction opposite to another end portion of the driving sourcethat is located at another end thereof opposite to the one end in theaxial direction of the driving source and fixed to the side frame.

With this configuration, when viewing the side frame from a side wherethe driving source is fixed to the side frame, the fixing portion doesnot overlap the driving source, so that the bracket can be easilyattached to the side frame and the driving source can be easily fixed tothe side frame.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a car seat as a vehicle seat accordingto one embodiment.

FIG. 2 is a perspective view of a seat frame embedded in the car seat.

FIG. 3 is a front view of a seat back frame constituting the seat frame.

FIG. 4 includes a perspective view (a) illustrating a connectingstructure by which a side frame of a seat back and a lower connectingwire are connected, and a sectional view (b) taken along the line X-X of(a).

FIG. 5 is a perspective view of a driving mechanism as viewed from therear side.

FIG. 6 is a perspective view of the driving mechanism as viewed from thefront side. FIG. 7 is an exploded perspective view of the drivingmechanism.

FIG. 8 includes a side view (a) of a driving source, and a sectionalview (b) taken along the line Y-Y of (a).

FIG. 9 is an enlarged top view of the driving mechanism.

FIG. 10 is a sectional view of a contact link member.

FIG. 11 includes explanatory views (a) to (c) for explaining theoperation of the driving mechanism when the car turns to the right.

FIG. 12 includes explanatory views (a) and (b) for explaining theoperations of the driving mechanism and the pressure-receiving memberwhen the car turns to the right.

FIG. 13 is a view illustrating the pressure-receiving member when thecar turns to the right and the driving mechanism is positioned in anadvanced position.

FIG. 14 is a view illustrating the positional relation in the verticaldirection between a seat back pad and a support portion.

FIG. 15 includes explanatory view (a) to (c) for explaining theoperation of the driving mechanism in a rear-end collision.

FIG. 16 includes explanatory views (a) to (c) for explaining theoperations of the driving mechanism and the pressure-receiving member inthe rear-end collision.

FIG. 17 is a sectional view of the contact link member according to amodified embodiment.

FIG. 18 shows a first modification and includes a top view (a)illustrating a cover member, the contact link member, and an upperconnecting wire, and a sectional view (b) thereof.

FIG. 19 shows a second modification and is a sectional view illustratingthe positional relation between the contact link member, thepressure-receiving member, and the side frame.

FIG. 20 shows a third modification and is a sectional view illustratingthe upper connecting wire and the pressure-receiving member.

FIG. 21 shows a fourth modification and is a view illustrating thepositional relation between the driving source and a torsion spring.

FIG. 22 shows a fifth modification and includes a front view (a)illustrating the pressure-receiving member and the seat back frame and asectional view (b) of the pressure-receiving member.

FIG. 23 shows a sixth modification and is a front view of thepressure-receiving member.

FIG. 24 shows a seventh modification and includes a side view (a)illustrating the seat back frame and a front view (b) illustrating thepressure-receiving member and the seat back frame.

FIG. 25 shows an eighth modification and includes a front viewillustrating the pressure-receiving member and the seat back frame.

FIG. 26 shows a ninth modification and is a perspective viewillustrating the side frame, the second bracket, and the driving source.

FIG. 27 shows a tenth modification and includes a perspective view (a)illustrating the side frame and the driving source and a sectional view(b) of the left end portion of the seat back.

DESCRIPTION OF EMBODIMENTS

One embodiment of the present invention will be described in detail withreference made to the drawings, where necessary.

As seen in FIG. 1, a vehicle seat according to this embodiment isconfigured as a car seat S used for a driver's seat and the like of anautomobile, and mainly includes a seat cushion S1, a seat back S2, and aheadrest S3.

A seat frame F shown in FIG. 2 as an example of a frame is embedded inthe seat cushion S1 and the seat back S2. The seat frame F mainlyincludes a seat cushion frame F1 constituting a frame of the seatcushion S1, and a seat back frame F2 constituting a frame of the seatback S2. The seat cushion S1 is configured such that the seat cushionframe F1 is covered with a cushion material made of urethane foam or thelike, and an outer skin material made of synthetic leather or fabric.The seat back S2 is configured such that the seat back frame F2 iscovered with a seat back pad BP made of a cushion material such asurethane foam (see FIG. 12 (a)) and an outer skin material.

The seat back frame F2 mainly includes an upper frame 10, right and leftside frames 20 constituting right and left frames of the seat back S2,and a lower frame 30; the upper frame 10, the right and left side frames20, and the lower frame 30 are joined together, for example, by weldingto thereby form a frame-like configuration.

The upper frame 10 is formed by bending a pipe material into asubstantially U-shape configuration and includes a lateral pipe portion11 extending in the lateral (right-left) direction, and a pair ofsupport brackets 12 for attachment of the headrest S3 are fixed bywelding to the lateral pipe portion 11. Right and left vertical pipeportions 13 of the upper frame 10 extend in the upper-lower direction;right and left side frame main body portions 21 are joined to lowerportions of the vertical pipe portions 13 by welding or the like andmade into integral parts to thereby form right and left side frames 20.

Right and left side frame main body portions 21 are arranged laterallyopposite to each other. Each of the right and left side frame main bodyportion 21 is made by press working sheet metal to have an approximatelyU-shaped cross section having a pair of front and rear bent portions21A; the front and rear bent portions 21A are formed by laterallyinwardly bending both end portions of the side frame main body portion21 located at both ends in the front-rear direction that is the widthdirection of the side frame main body portion 21. Each of the side framemain body portions 21 is connected to the corresponding vertical pipeportion 13 with its upper portion holding the vertical pipe portion 13,and the lower portion of the side frame main body portion 21 protrudesfrontward farther than the upper portion of the side frame main bodyportion 21 to provide a bulging portion 22.

As seen in FIG. 3, a pressure-receiving member 40 as an example of amovable member and a pair of right and left driving mechanisms 50 aredisposed between the right and left side frames 20. Further, acontroller 80 (see FIG. 5) for controlling the driving mechanisms 50(driving sources 52) is provided inside or outside the car seat S.

The pressure-receiving member 40 is a member for receiving a load froman occupant seated on the car seat S through the outer skin material andthe seat back pad BP. The pressure-receiving member 40 is made ofplastic resin or the like to allow elastic deformation, and includes apressure-receiving portion 41 disposed to face the back of the occupant,and right and left support portions 42 extending obliquely frontwardtoward laterally outside directions from upper portions of both rightand left ends of the pressure-receiving portion 41; thepressure-receiving portion 41 and the right and left support portions 42are integrally formed with each other. The pressure-receiving member 40includes a first portion 40A composed of a lower portion of thepressure-receiving portion 41 and configured to support the lumbarregion of the occupant, a second portion 40B composed of an upperportion of the pressure-receiving portion 41 and the right and leftsupport portions 42 and configured to support the occupant at a positionabove the first portion 40A, and a third portion 40C composed of amiddle portion located in the middle of the pressure-receiving portion41 in the upper-lower direction and configured to connect the firstportion 40A and the second portion 40B.

The third portion 40C is provided at a laterally center portion of thepressure-receiving member 40. The lateral width of the third portion 40Cis smaller than that of the first portion 40A and that of the secondportion 40B. In other words, the pressure-receiving member 40 is shapedsuch that the middle portion thereof in the upper-lower direction isnarrowed at the third portion 40C.

The lateral width of the first portion 40A is larger than that of thethird portion 40C. Widening the lateral width of the first portion 40Amakes it possible to stably support the lumbar region of the occupant bythe first portion 40A.

The pressure-receiving member 40 is configured such that thepressure-receiving portion 41 has a first bead B1 protruding rearwardand each of the support portions 42 has second beads B2 protrudingrearward. Providing the beads B1, B2 on the pressure-receiving member 40makes it possible to enhance the rigidity of the pressure-receivingmember 40.

The first bead B1 is shaped to recess as viewed from the front side. Thefirst bead B1 consists of a plurality of vertical bead portions B11extending in the upper-lower direction on the third portion 40C, and aconnecting bead portion B12 extending laterally to connect the pluralityof vertical bead portions B11. Each of the vertical bead portions B11extends from the second portion 40B to the first portion 40A via thethird portion 40C. The laterally outermost vertical bead portions B11extend into the second portion 40B, and upper end portions thereof arearranged at an upper portion of the second portion 40B.

The second beads B2 are shaped to recess as viewed from the front side.The second beads B2 are formed at a plurality of locations and spacedapart from each other in the upper-lower direction; the second beads B2extend from laterally outer end portions of the support portions 42toward the first bead B1 and are connected to the laterally outermostvertical bead portions B11. This configuration makes it possible toenhance the rigidity at the boundary (portions bent along theillustrated line) between the pressure-receiving portion 41 and thesupport portions 42.

The second beads B2 extend diagonally relative to the horizontal plane.To be more specific, the second beads B2 extend obliquely from the firstbead B1 in laterally outward and upward directions.

Further, at each boundary located between the pressure-receiving portion41 and the support portion 42, a relief portion 44 having a recessedrear surface is formed in a position corresponding to an upperconnecting wire W1 which will be described later (see also FIG. 5). Inthis embodiment, the relief portion 44 is located in a positionoverlapping the second bead B2 that is provided in the middle portion inthe upper-lower direction.

The pressure-receiving member 40 is connected in such a manner as to bemovable in the front-rear direction relative to the right and left sideframes 20 via upper and lower connecting wires W1, W2 as an example ofelastic members.

The upper connecting wire W1 extends at the rear side of thepressure-receiving member 40 from one support portion 42 to the othersupport portion 42. Namely, the upper connecting wire W1 is provided tohold the second portion 40B from the rear side between right and leftend portions of the second portion 40B. Further, the upper connectingwire W1 is bent such that a laterally center portion thereof protrudesdownward. To be more specific, the upper connecting wire W1 is providedcorresponding to the upper portion of the pressure-receiving portion 41,and includes a downwardly-protruding U-shaped bent portion W11, and sideportions W12 extending laterally outward from right and left ends of thebent portion W11. The lower portion of the bent portion W11 ispositioned lower than the contact position (relief portion 44) at whichthe upper connecting wire W1 contacts the pressure-receiving member 40,more specifically, positioned substantially at the same height as thelower end of the support portion 42. End portions of the upperconnecting wire W1 are connected to the driving mechanisms 50 fixed tothe side frames 20 respectively, and by engaging engagement hooks (notshown) formed on an upper portion of the rear surface of thepressure-receiving member 40 with the upper connecting wire W1, theupper portion of the pressure-receiving member 40 is connected to theright and left side frames 20.

End portions of the lower connecting wire W2 are connected to wireattachment portions 23 (see FIG. 4) which are provided on the sideframes 20 respectively, and by engaging engagement hooks (not shown)formed on a lower portion of the rear surface of the pressure-receivingmember 40 with the lower connecting wire W2, the lower portion of thepressure-receiving member 40 is connected to the right and left sideframes 20.

As seen in FIGS. 4 (a) and (b), the wire attachment portion 23 is formedby bending sheet metal or the like, and a fixing piece 23A thereof isfixed to a laterally inner surface of the side frame main body portion21 by welding, a screw, or the like. The wire attachment portion 23includes the fixing piece 23A, a connecting piece 23B extendinglaterally inward from an upper end portion of the fixing piece 23A, andan engagement piece 23C extending upward from a laterally inner endportion of the connecting piece 23B. An oblong hole 23D extending longin the front-rear direction and approximately in the shape of an oval isformed in the engagement piece 23C, and by engaging the end portion ofthe lower connecting wire W2 into the oblong hole 23D, the lowerconnecting wire W2 is connected to the side frame 20. Further, a plasticspacer 23E is engaged into the oblong hole 23D at the front of the lowerconnecting wire W2 to thereby prevent the lower connecting wire W2 frommoving frontward and rearward within the oblong hole 23D.

As seen in FIG. 12 (a), the seat back pad BP includes a central padportion BP1 disposed to face the pressure-receiving portion 41, andright and left side pad portions BP2 provided at both right and leftsides of the central pad portion BP1 and configured to protrudefrontward farther than the central pad portion BP1.

The side pad portion BP2 extends laterally outward from the central padportion BP1 along the support portion 42 of the pressure-receivingmember 40, and then extends rearward along the laterally outer side ofthe side frame 20, and finally extends laterally inward at the rear sideof the side frame 20. The side pad portion BP2 has a space formedbetween the support portion 42 of the pressure-receiving member 40 andthe side frame 20, so that the driving mechanism 50 disposed in thisspace is prevented from contacting the seat back pad BP.

A first tuck-in groove BP3 is provided between the central pad portionBP1 and each of the side pad portions BP2. The first tuck-in groove BP3is a groove that is recessed as viewed from the front side and extendsin the upper-lower direction. Provided at a bottom portion of the firsttuck-in groove BP3 are outer skin attachment members (not shown)disposed vertically for allowing the outer skin material of the seatback S2 to be tucked in the first tuck-in groove BP3. As viewed from thefront-rear direction, the first tuck-in grooves BP3 are provided atpositions overlapping the right and left end portions of thepressure-receiving member 40. Namely, the pressure-receiving member 40extends laterally outward from the inner region to the outer region ofthe first tuck-in grooves BP3, and the support portions 42 are locatedlaterally outside the first tuck-in grooves BP3.

Further, as seen in FIG. 14, a pair of second tuck-in grooves BP4 areprovided in the central pad portion BP1 approximately at a centerportion thereof in the upper-lower direction. Each second tuck-in grooveBP4 is a groove that is recessed as viewed from the front side andextends in the right-left direction (lateral direction). Provided at abottom portion of the second tuck-in groove BP4 are outer skinattachment members (not shown) disposed laterally for allowing the outerskin material of the seat back S2 to be tucked in the second tuck-ingroove BP4. The pair of second tuck-in grooves BP4 are provided atpositions above and below the support portions 42, respectively, of thepressure-receiving member 40. Namely, the support portions 42 and theupper connecting wire W1 are provided at the same height position asthat of the region between the pair of second tuck-in grooves BP4.According to this embodiment, the entire support portions 42 areprovided at the same height as the region between the pair of secondtuck-in grooves BP4; however, the support portions 42 may be providedsuch that only part thereof is positioned at the same height as theregion between the pair of second tuck-in grooves BP4.

As seen in FIG. 3, the driving mechanism 50 is a mechanism for actuatingthe pressure-receiving member 40, and is provided at each of the rightand left side frames and arranged on both right and left sides of thepressure-receiving member 40. Although details thereof will be describedlater, the driving mechanism 50 is configured to move the right endportion or the left end portion of the pressure-receiving member 40 froman initial position as shown in FIG. 12 (a) to an advanced position thatis located frontward of the initial position as shown in FIG. 13 toorient the pressure-receiving member 40 to the right or to the left, orto move (return) the same from the advanced portion to the initialposition. Further, the driving mechanism 50 (linkage 51) is configuredto operate when a load equal to or greater than a predetermined amountis input from an occupant to the pressure-receiving member 40 to causethe pressure-receiving member 40, to move to a backward position asshown in FIG. 16 (c) that is located rearward of an initial position ofthe pressure-receiving member 40 as shown in FIG. 16 (a).

As seen in FIG. 5, the driving mechanism 50 mainly includes a linkage 51connected to the pressure-receiving member 40 via the upper connectingwire W1, and a driving source 52 configured to actuate the linkage 51.The right and left driving mechanisms 50 are substantially symmetricalin structure, and the left-side driving mechanism 50 will be mainlyexplained in detail in the following description with reference to thedrawings.

As seen in FIGS. 6 and 7, the driving source 52 mainly includes a motor52A, a gearbox 52B, and an output shaft 52C; the driving source 52 isfixed to the side frame 20 via a bracket 60. The driving source 52 isdisposed in such a position as not to get in contact with thepressure-receiving member 40.

The motor 52A is configured such that widths thereof in the lateraldirection as well as in the front-rear direction are smaller than thoseof the gearbox 52B that is disposed on an upper portion of the motor52A. Namely, the driving source 52 is narrower at its lower portion(motor 52A) than at its upper portion (gearbox 52B).

The gearbox 52B is a member for accommodating a train of gears (notshown) configured to reduce a speed with which a rotary driving forcegenerated by the motor 52A is transmitted therethrough, and mainlyincludes a box body 310 approximately in the shape of a tube, and a lidmember 320 configured to close an upper end portion (at an end portionin the axial direction of the output shaft 52C) of the box body 310.Provided at side surfaces of the box body 310 and the lid member 320 arethree fastening portions 330 each protruding radially outward of theoutput shaft 52C. The fastening portion 330 is a portion in which ascrew 91 as an example of a fastening member for fastening the box body310 and the lid member 320 is disposed. The fastening portions 330 arearranged on the side surface of the gearbox 52B at equally-spacedintervals in a circumferential direction of the gearbox 52B.

The output shaft 52C is a shaft for outputting the rotary driving forceof the motor 52A, the speed of which has been reduced by the gearbox52B. The output shaft 52C is disposed through the lid member 320.

The structure of the bracket 60 by which the driving source 52 (drivingmechanism 50) is fixed to the side frame 20 will be described.

The bracket 60 consists of a first bracket 61 and a second bracket 62.Each of the first bracket 61 and the second bracket 62 is made by pressworking sheet metal to have an approximately L-shaped cross section, andmainly includes an engagement portion 61A, 62A and a fixing portion 61B,62B.

The engagement portion 61A of the first bracket 61 is a portion engagedwith an upper end portion (lid member 320) of the gearbox 52B that is aportion of the driving source 52 located at one end in the axialdirection thereof; the engagement portion 61A is approximately in theshape of a circular disk having an engagement hole. The fixing portion61B is a portion fixed to the side frame 20, and extends along the sideframe 20 from a laterally outer end portion (end portion located nearthe side frame 20) of the engagement portion 61A toward an upper sideopposite to a lower side on which a portion of the driving source 52located at the other end in the axial direction thereof (opposite to theone end) is located. The fixing portion 61B has a circular hole 61Hthrough which a bolt 92 for fixing the first bracket 61 to the sideframe 20 is inserted.

The engagement portion 62A of the second bracket 62 is a portion engagedwith the motor 52A of the driving source 52, and is approximately in theshape of a frame. The fixing portion 62B is a portion fixed to the sideframe 20, and extends downward along the side frame 20 from a laterallyouter end portion of the engagement portion 62A. As seen in FIG. 8 (a),the fixing portion 62B has an extension portion 62C extending frontward(in a direction orthogonal to the axial direction) farther than thedriving source 52 when viewing the side frame 20 laterally from theinner side. The extension portion 62C has a circular hole 62H (see FIG.7) through which a bolt 93 for fixing the second bracket 62 to the sideframe 20 is inserted.

As seen in FIG. 7, the first bracket 61 is fixed to the driving source52 with the engagement portion 61A being engaged with the upper endportion of the gearbox 52B and fastened to the gearbox 52B by threebolts 94 (only one of them is shown in the figure), whereas the secondbracket 62 is fixed to the driving source 52 with the engagement portion62A being engaged with the motor 52A and fastened to the gearbox 52B bythree screws 95 (only one of them is shown in the figure). Further, asseen in FIG. 8 (a), the driving source 52 is fixed to the side frame 20with the fixing portion 61B being fixed to the side frame 20 by a bolt92 and with the fixing portion 62B being fixed at its extension portion62C to the side frame 20 by a bolt 93.

In this embodiment, when viewing the side frame 20 shown in FIG. 8 (a)from a side where the driving source 52 is fixed to the side frame 20,the fixing portion 61B and the extension portion 62C do not overlap thedriving source 52 (extend outward beyond the driving source 52), so thatthe bracket 60 can be easily attached to the side frame 20 by the bolts92, 93. Accordingly, the driving source 52 can be easily fixed to theside frame 20. Further, the driving source 52 can be stably fixed to theside frame 20 by means of the two brackets, i.e., the first bracket 61and the second bracket 62.

The extension portion 62C has a front end portion disposed on thebulging portion 22 of the side frame 20. This configuration makes itunnecessary to provide the side frame 20 with a dedicated portion onwhich the extension portion 62C extending frontward beyond the drivingsource 52 is disposed, so that the structure of the side frame 20 can besimplified and a compact structure can be provided around the drivingsource 52.

As seen in FIG. 8 (b), the driving source 52 fixed to the side frame 20via the bracket 60 is located such that as viewed from an axialdirection of the output shaft 52C, all the three fastening portions 330are arranged at positions avoiding a line LN (shown by the alternatelong and short dash line) connecting the ends of the pair of bentportions 21A of the side frame 20. To be more specific, as viewed fromthe axial direction, the fastening portions 330 are provided such thatat least one fastening portion 330 is arranged on each side of the lineLN, and more specifically, one at a laterally outer side of the line LNand two at a laterally inner side of the line LN.

The first bracket 61 (engagement portion 61A) has a size such that asviewed from the axial direction, the laterally inner end 61E thereofdoes not protrude laterally inward from the laterally inner end 52E ofthe driving source 52. With this configuration, the first bracket 61does not protrude on an occupant's side, so that a compact structure canbe provided around the driving source 52.

As shown in FIG. 7, the linkage 51 is rotatable substantially in thefront-rear direction relative to the side frame 20, and mainly includestwo links for actuating the pressure-receiving member 40, morespecifically, a drive link member 100 as an example of a second linkmember and a contact link member 200 as an example of a link member.

The drive link member 100 is a member made of metal and in the shape ofa long plate, and mainly includes a shaft hole 110 formed in one endportion thereof, a pin-insertion hole 120 formed in the other endportion thereof, and a stopper portion 130. The drive link member 100 isfastened to the driving source 52 with the shaft hole 110 beingconnected to (e.g., serration-fitted onto) the output shaft 52C of thedriving source 52 and the output shaft 52C being clipped by an E-ring 53to prevent the drive link member 100 from coming off the output shaft52C. With this configuration, the drive link member 100 rotatessubstantially in the front-rear direction when the driving source 52 isdriven.

The stopper portion 130 is a portion configured to contact a memberfixed to the side frame 20, specifically a fixed stopper member 70 to bedescribed later, to restrict a rotation of the drive link member 100itself. To be more specific, the stopper portion 130 includes a firststopper portion 131 configured to restrict a rotation of the drive linkmember 100 in a forward direction (in one direction) and a secondstopper portion 132 configured to restrict a rotation of the drive linkmember 100 in a rearward direction (in a direction opposite to the onedirection).

As seen in FIG. 9, the first stopper portion 131 and the second stopperportion 132 are provided, as viewed from a direction of the axis ofrotation of the drive link member 100 (axial direction of the outputshaft 52C), at an outer peripheral portion of the drive link member 100,in other words, at a contour portion of the drive link member 100.Furthermore, the first stopper portion 131 and the second stopperportion 132 are provided on a side surface 102 which surrounds theoutput shaft 52C that is an axis of rotation of the drive link member100. To be more specific, the first stopper portion 131 protrudessubstantially frontward from the front side of the long main bodyportion 101 when the drive link member 100 takes a posture shown in FIG.9 (i.e., when the pressure-receiving member 40 is in an initialposition); that surface of the first stopper portion 131 which contactsthe fixed stopper member 70 is substantially flat. Further, in thisposture of the drive link member 100, the second stopper portion 132protrudes substantially leftward from the rear side of the main bodyportion 101; that surface of the second stopper portion 132 whichcontacts the fixed stopper member 70 is substantially flat.

The structure of the fixed stopper member 70 will be described.

The fixed stopper member 70 is a member for restricting a rotation ofthe drive link member 100 by the stopper portion 130 coming into contactwith the fixed stopper member 70; the fixed stopper member 70 is fixedto the side frame 20. To be more specific, the fixed stopper member 70is disposed between the output shaft 52C and the side frame 20; asviewed form the axial direction of the output shaft 52C, the fixedstopper member 70 has the shape of the letter U opening toward thelaterally inner side that is a side where the drive link member 100 isdisposed. The fixed stopper member 70 is fixed to the side frame 20 viathe first bracket 61 with a proximal portion 72 of the fixed stoppermember 70 (that is located opposite to end portions 71 of the letter U)being fixed to the first bracket 61 by welding or the like.

The fixed stopper member 70 has a rotation-restricting portion 73 ateach of its end portions 71 such that the stopper portion of the drivelink member 100 can come into contact with the rotation-restrictingportions 73. Each rotation-restricting portion 73 is approximately inthe shape of a rectangular tube and engageable onto the end portion 71;the rotation-restricting portion 73 is made of plastic resin. The drivelink member 100 is configured such that a frontward rotation thereof(i.e., rotation of the drive link member 100 toward the front side) isrestricted with the first stopper portion 131 coming into contact withthe front-side rotation-restricting portion 73 (see FIG. 11 (c)),whereas a rearward rotation thereof (i.e., rotation of the drive linkmember 100 toward the rear side) is restricted with the second stopper132 coming into contact with the rear-side rotation-restricting portion73. Since the rotation-restricting portions 73 are made of plasticresin, contact noise generated between the stopper portion 130 and thefixed stopper member 70 can be suppressed, so that noise produced by theactuation of the drive link member 100 can be suppressed.

Further, as viewed from the axial direction of the output shaft 52C,each of the rotation-restricting portions 73 is located within agenerally circular-shaped contour of the driving source 52. This makesit possible to suppress upsizing of the drive link member 100 having theside surface 102 on which is provided the stopper portion 130contactable with the rotation-restricting portions 73, so that a compactstructure of the drive link member 100 can be provided.

As viewed from the axial direction, the output shaft 52C is so disposedas to face an opening 74 of the U-shaped fixed stopper member 70. Thismakes it possible to arrange the drive link member 100 and the fixedstopper member 70 laterally adjacent to each other, so that a compactstructure can be provided around the drive link member 100.

Further, as viewed from the axial direction of the output shaft 52C, thestopper portion 130 is disposed inside a circle C (shown by thealternate long and short dash line); the circle C is defined such thatthe center of the circle C coincides with the rotation center C1 of thedrive link member 100 and the radius of the circle C corresponds to thedistance from the rotation center C1 to the rotation center C2 of thecontact link member 200. With this configuration, upsizing of the drivelink member 100 can be suppressed and a compact structure of the drivelink member 100 can be provided.

In this embodiment, the right and left drive link members 100 are eachprovided using a common part. To be more specific, the drive link member100 constituting the left-side driving mechanism 50 shown in FIG. 9 canbe used as the right-side driving mechanism 50 by reversing it orplacing the reverse side obverse. This configuration is achieved becausethe stopper portion 130 is provided on the side surface 102 of theplate-like drive link member 100 but does not protrude only in one sidein the axial direction. Using the common part makes it possible toreduce the number of parts and to save the effort of parts management,so that reduction in the cost can be achieved. Further, the mix-upbetween the right and left parts can be prevented and the assembling isfacilitated.

As seen in FIG. 7, the contact link member 200 is a member in the shapeof a long plate, and mainly includes a stopper 210 and a pin-insertionhole 220 formed in one end portion thereof, a contact portion 230provided on the other end portion thereof, and a through-hole 240 formedin a region between the pin-insertion hole 220 and the contact portion230. The contact link member 200 rotates substantially in the front-reardirection relative to the drive link member 100 with the pin 54 beingengaged into the pin-insertion hole 220 and the pin-insertion hole 120of the drive link member 100. Further, the contact link member 200 isconnected to the pressure-receiving member 40 via the upper connectingwire W1 with an end portion of the upper connecting wire W1 beinginserted into the through-hole 240.

The contact portion 230 is a portion configured to contact thepressure-receiving member 40 when the driving source 52 actuates thepressure-receiving member 40. As seen in FIG. 9, the contact portion 230has a convexly curved shape as viewed from a direction of the axis ofrotation of the contact link member 200. Further, as seen in FIG. 10,the contact portion 230 also has a convexly curved shape as viewed fromany direction orthogonal to the direction of the axis of rotation. To bemore specific, the contact portion 230 is approximately spherical inshape.

When the pressure-receiving member 40 is in the initial position (asshown by the solid line in FIG. 9) and a load is not input from anoccupant to the pressure-receiving member 40 (i.e., when an occupant isnot seated on the car seat S), the pressure-receiving member 40 isspaced apart from the contact portion 230. When an occupant sits on thecar seat S and a load is input from the occupant to thepressure-receiving member 40 in the initial position, the supportportion 42 deforms as shown by the chain double-dashed line and contactsthe contact portion 230. With this configuration, since deformation ormovement of the pressure-receiving member 40 is allowed until thepressure-receiving member 40 comes into contact with the contact portion230, the cushionability of the seat back S2 can be improved. Thepressure-receiving member 40 has a contact surface 43, with which thecontact portion 230 comes into contact, at the rear surface of thesupport portion 42. As viewed from the direction of the axis of rotationof the contact link member 200, the contact surface 43 has a concavelycurved shape.

Further, because of the provision of the relief portion 44, the supportportion 42 has, at the same height position as the height of theposition of the upper connecting wire W1, a first support portion 45extending in a diagonally leftward and frontward direction from thepressure-receiving portion 41, and a second support portion 46 extendingfurther in a diagonally leftward and frontward direction from alaterally outward end portion of the first support portion 45. Thecontact surface 43 is provided on the second support portion 46. Theupper connecting wire W1 is bent at a portion corresponding to aboundary between the pressure-receiving portion 41 and the first supportportion 45, and contiguously in contact with the pressure-receivingportion 41 and the first support portion 45.

The contact portion 230 of the contact link member 200 is provided, asseen in FIGS. 12 (a) and (b), so as to contact the contact surface 43 ofthe pressure-receiving member 40 at a position laterally outward of thetuck-in groove BP3 of the seat back pad BP. The seat back pad BP isthinner at a potion where the tuck-in groove BP3 is formed, and iseasily deformable at this thinner portion. With this configuration, whenthe contact portion 230 pushes the support portion 42 of thepressure-receiving member 40 forward, the side pad portion BP2 of theseat back pad BP can be pushed forward with a small force.

Returning to FIG. 9, the stopper 210 is a portion configured to contactthe side surface 102 of the drive link member 100 to restrict the amountof rearward rotation of the contact link member 200 (see FIG. 11 (c) andFIG. 15 (c)). The stopper 210 protrudes out from one end portion of thecontact link member 200 and is bent downward at the distal end of thisprotruding portion toward the lower side where the drive link member 100is disposed.

As seen in FIG. 10, the contact link member 200 includes a link body 201having the shape of a long plate, and a cover member 202 entirelycovering the link body 201. The link body 201 and the cover member 202are made of different materials. To be more specific, the contact linkmember 200 is made by insert molding or the like; the link body 201 ismade of metal and the cover member 202 is made of plastic resin. Thethrough-hole 240 is formed through the link body 201 and the covermember 202. The contact portion 230 is provided on the cover member 202and formed as a part of the cover member 202. Accordingly, the contactportion 230 is made of plastic resin.

As seen in FIG. 9, the contact link member 200 is formed such that thelength from the rotation center C2 thereof to the contact portion 230 islonger than the length from the rotation center C2 to the rotationcenter C1 of the drive link member 100.

As seen in FIGS. 6 and 7, a torsion spring 55 as an urging member isdisposed between (in terms of its mechanics between) the drive linkmember 100 and the contact link member 200. The torsion spring 55 is amember configured to urge the contact link member 200 to rotatefrontward (in one direction), and includes a coil portion 55A disposedon the contact link member 200 (i.e., on the opposite side of thecontact link member 200 from the driving source 52, a first arm portion55B extending radially outward from an upper end of the coil portion 55Aand bent downward at its distal end to provide an approximately L-shapedconfiguration, and a second arm portion 55C extending radially outwardfrom a lower end of the coil portion 55A and bent downward at its distalend to provide an L-shaped configuration.

The torsion spring 55 is positioned with the coil portion 55A thereofbeing engaged by the pin 54, with the first arm portion 55B as one endof the torsion spring 55 being hooked onto the first stopper portion 131of the drive link member 100, and with the second arm portion 55C as theother end of the torsion spring 55 being hooked onto the stopper 210 ofthe contact link member 200. With this configuration, the torsion spring55 generates an urging force to rotate the contact link member 200 in adirection shown by the arrow in FIG. 9.

The torsion spring 55 and the upper connecting wire W1 as an example ofa connecting wire serve as a member for restricting a rearward rotationof the contact link member 200, in other words, a member (rotationresistive member) to provide resistance against the rearward rotation.To be more specific, the torsion spring 55 urges the contact link member200 to rotate frontward, to thereby restrict a rearward rotation of thecontact link member 200.

Further, the upper connecting wire W1 has right and left end portions,both of which are bent diagonally frontward, and a downwardly extendingend portion of each end portion is coupled into the through-opening 240of the contact link member 200, so that the upper connecting wire W1connects the pressure-receiving member 40 and the contact link member200. Further, a connecting portion C3 connecting the contact link member200 and the pressure-receiving member 40 is located, when thepressure-receiving member 40 is in the initial position shown in FIG. 9,at a front end portion of the contact link member 200, morespecifically, at a position frontward of the rotation center C2 of thecontact link member 200, so that the upper connecting wire W1 urges thecontact link member 200 to rotate frontward; this can restrict arearward rotation of the contact link member 200.

The coil portion 55A of the torsion spring 55 is so located as to facethe relief portion 44 of the pressure-receiving member 40 (see FIG. 5).This configuration suppresses a noise which would occur when thepressure-receiving member 40 deforms, and can serve to make effectiveuse of the space.

As viewed along the upper-lower direction, the coil portion 55A of thetorsion spring 55 overlaps part of the driving source 52, morespecifically, the fastening portion 330. This makes it possible todownsize the driving mechanism 50 in the horizontal direction. Further,the coil portion 55A is spaced apart from the upper connecting wire W1.This arrangement can reduce the possibility of undesired engagement ofthe upper connecting wire W1 with the coil portion 55A when the upperconnecting wire moves backward.

When the pressure-receiving member 40 is in the initial position asshown in FIG. 9, the connecting portion C3 is located inside the circleC shown by the alternate long and short dash line, as viewed from thedirection of the axis of rotation of the contact link member 200.Further, the connecting portion C3 is located laterally outward of therotation center C2 of the contact link member 200 when thepressure-receiving member 40 is in the initial position.

The driving mechanisms 50 configured as described above areindependently operable at the right-side and at the left-side. To bemore specific, the driving sources 52 are controlled by the controller80 so that the right-side driving source 52 and the left-side drivingsource 52 are independently driven, and the drive link member 100 andthe contact link member 200 of the right-side linkage 51 and the drivelink member 100 and the contact link member 200 of the left-side linkage51 are independently rotatable. Namely, the driving mechanisms 50 arenot configured such that, for example, when the left-side drive linkmember 100 and the left-side contact link member 200 rotate, theright-side drive link member 100 and the right-side contact link member200 rotate in an interlocking manner.

As seen in FIG. 5, the controller 80 is configured to control theactuation of each driving source 52 (motor 52A) so that thepressure-receiving member 40 disposed in the seat back S2 is orientedtoward a turning direction (see FIG. 13). Although various controlmethods are available with the controller 80, as an example, lateralacceleration and turning direction may be obtained based on signals fromwheel speed sensors and a steering angle sensor, and if the thusobtained lateral acceleration exceeds a predetermined threshold value,then the motor 52A of the driving mechanism 50 located at the outer sidein the turning direction is driven, to thereby orient thepressure-receiving member 40 toward the turning direction.

In this embodiment, the controller 80 monitors electric current flowingthrough the motor 52A during the operation of the motor 52A, and stopsthe supply of electric current to the motor 52A to stop the operation ofthe motor 52A. When the drive link member 100 rotates until the stopperportion 130 contacts the fixed stopper member 70, the motor 52A stopsand the electric current flowing through the motor 52A becomes large.The controller 80 detects this condition and stops the supply ofelectric current to the motor 52A. This configuration makes it possiblewith a simple structure to cause the stopper portion 130 toappropriately work as well as to precisely regulate the amount ofrotation of the drive link member 100.

Next, operations of the driving mechanism 50 and the pressure-receivingmember 40 during cornering of the car will be described.

When the car turns to the right, the controller 80 actuates the drivingsource 52 of the left-side driving mechanism 50. This causes the drivelink member 100 to rotate frontward from the posture shown in FIG. 11(a) to the postures shown in FIGS. 11 (b) and (c), so that the contactlink member 200 moves frontward while rotating relative to the drivelink member 100. Accordingly, the left end portion (connecting portionC3) of the upper connecting wire W1 moves frontward to thereby cause theleft-side support portion 42 (left end portion) of thepressure-receiving member 40 to move from the initial position to theadvanced position that is located frontward of the initial position.

The first stopper portion 131 of the drive link member 100 then comesinto contact with the front-side rotation-restricting portion 73 of thefixed stopper member 70, so that the rotation of the drive link member100 is restricted, and the stopper 210 of the contact link member 200comes into contact with the side surface 102 of the drive link member100, so that the rotation of the contact link member 200 is restricted.In so doing, the electric current flowing through the driving source 52exceeds the predetermined value, and the controller 80 stops theoperation of the driving source 52.

Accordingly, as seen in FIGS. 12 (a), (b) and 13, the left end portionof the pressure-receiving member 40 moves from the initial position tothe advanced position, so that the entire pressure-receiving member 40is oriented to the turning direction, i.e., to the right-side. As aresult, the centrifugal force applied to the occupant during corneringcan be appropriately supported by the seat back S2.

To be more specific, as seen in FIG. 3, when the support portion 42 ofthe pressure-receiving member 40 moves from the initial position to theadvanced position, the lower portion of the pressure-receiving portion41, that is, the first portion 40A does not move in the front-reardirection because the first portion 40A is supported by the lowerconnecting wire W2 that is fixed to the side frames 20 (and does notmove at least by the operation of the driving mechanism 50). This causesthe pressure-receiving member 40 to get twisted at the third portion 40Cthat is located between the first portion 40A and the second portion 40Bhaving the support portions 42. In this embodiment, since the lateralwidth of the third portion 40C is smaller than that of the first portion40A and that of the second portion 40B, the pressure-receiving member 40easily gets twisted at the third portion 40C. With this configuration,the support portions 42 can move smoothly between the initial positionand the advanced position.

It is to be noted that since the first bead B1 is provided on the thirdportion 40C, a plastic deformation of the pressure-receiving member 40can be suppressed when it is twisted. Further, the first bead B1 extendsin the upper-lower direction, which does not prevent thepressure-receiving member 40 from being twisted at the third portion40C.

Further, the first portion 40A and the second portion 40B are connectedat the third portion 40C, so that an uncomfortable feeling experiencedby the occupant when the support portions 42 move can be suppressed, ascompared with an alternative configuration in which the first portion40A and the second portion 40B are not connected.

In this embodiment, since the linkage 51 consists of the drive linkmember 100 and the contact link member 200, when comparing with analternative configuration in which the upper connecting wire W1 isdirectly connected to one link member (e.g., drive link member 100 shownin FIG. 11) to move the pressure-receiving member 40 in the front-reardirection, a long travel distance of the left end portion of the upperconnecting wire W1 in the front-rear direction can be ensured. Thismakes it possible to ensure a sufficient travel distance (amount ofinclination) of the pressure-receiving member 40, so that thecentrifugal force applied to the occupant during cornering can befavorably supported by the pressure-receiving member 40.

Further, in this embodiment, when the pressure-receiving member 40 is inthe initial position, the connecting portion C3 is located laterallyoutward of the rotation center C2 and the contact link member 200 isurged to rotate frontward by the upper connecting wire W1 and otherparts, so that the contact link member 200 is unlikely to rotaterearward. This configuration can prevent the distal end of the contactlink member 200 from unsteadily moving when the pressure-receivingmember 40 is moved from the initial position to the advanced position,so that a stable movement of the pressure-receiving member 40 can beensured.

In this embodiment, as seen in FIG. 11 (c), the contact link member 200in the advanced position takes a posture such that the laterally outerend portion 231 of the contact portion 230 is located laterally outwardof the lateral end 49 of the support portion 42 of thepressure-receiving member 40. With this arrangement, the contact linkmember 200 supports the end portion of the support portion 42 of thepressure-receiving member 40, so that the pressure-receiving member 40can be stably supported by the contact link member 200.

Further, in the advanced position, the connecting portion C3 connectingthe contact link member 200 and the upper connecting wire W1 is locatedlaterally outward of a first imaginary line L1 connecting the contactpoint P of the contact portion 230 and the pressure-receiving member 40and the rotation center C2 of the contact link member 200. With thisarrangement, the contact link member 200 can support thepressure-receiving member 40 at a position as laterally outward aspossible, so that the pressure-receiving member 40 can be stablysupported by the contact link member 200.

Further, in the advanced position, the rotation center C2 of the contactlink member 200 is located laterally inward of a second imaginary lineL2 connecting the contact point P of the contact portion 230 and thepressure-receiving member 40 and the shaft center C4 (rotation center ofthe drive link member 100) of the driving source 52. This arrangementcan suppress an excessive rotation of the contact link member 200 in theclockwise direction of FIG. 11 when a load is applied in the advancedposition from the occupant to the left-side support portion 42 of thepressure-receiving member 40.

In this embodiment, as seen in FIG. 13, the contact link member 200rotates to such an extent that in the advanced position, the contactpoint P of the contact link member 200 and the pressure-receiving member40 is located frontward farther than the front end of the side frame 20.With this configuration, sufficient amount of frontward displacement ofthe contact link member 200 can be ensured.

As seen in FIGS. 12 and 13, the driving mechanism 50 is disposed in aspace of the seat back pad BP formed between the pressure-receivingmember 40 and the side frame 20 and is configured such that the contactlink member 200 does not contact the seat back pad BP even when thecontact link member 200 rotates. This configuration can suppressabnormal noise which would occur when the contact link member 200contacts the seat back pad BP.

Further, as seen in FIG. 14, the seat back pad BP is thinner at a potionwhere the pair of second tuck-in grooves BP4 are formed and thus aportion between the pair of second tuck-in grooves BP4 is easily causedto sag. The support portions 42 of the pressure-receiving member 40 andthe upper connecting wire W1 are provided at the same height as that ofthe portion between the pair of second tuck-in grooves BP4, so that whenthe support portions 42 and the upper connecting wire W1 are moved, theseat back pad BP is easily deformable in accordance with the movementsthereof.

When the car is to be shifted from turning state to straight travellingstate, the controller 80 drives the driving source 52 of the left-sidedriving mechanism 50 to rotate in a direction reverse to that in whichit rotates in the turning state. This causes the drive link member 100to rotate rearward from the posture shown in FIG. 11 (c) to the posturesshown in FIGS. 11 (b) and (a). The contact link member 200 then movesrearward while rotating relative to the drive link member 100 by theload applied from the occupant to the pressure-receiving member 40. Thiscauses the left end portion of the upper connecting wire W1 to moverearward, and the left-side support portion 42 of the pressure-receivingmember 40 is moved from the advanced position to the initial position.

Further, the second stopper portion 132 of the drive link member 100comes into contact with the rear-side rotation-restricting portion 73 ofthe fixed stopper member 70, so that the rotation of the drive linkmember 100 is restricted. In so doing, the electric current flowingthrough the driving source 52 exceeds the predetermined value, and thecontroller 80 stops the operation of the driving source 52. Accordingly,the pressure-receiving member 40 returns from the posture shown in FIG.13, in which the pressure-receiving member 40 is oriented to the right,to the posture shown in FIG. 12 (a), in which the pressure-receivingmember 40 faces the front.

On the other hand, when the car turns to the left, the controller 80actuates the driving source 52 of the right-side driving mechanism 50.The subsequent operations of the pressure-receiving member 40 and theright-side driving mechanism 50 are similar to those in the right turn,and therefore detailed description thereof will be omitted.

In this embodiment, the pressure-receiving member 40 is configured suchthat when an occupant sits on the car seat S and the pressure-receivingmember 40 contacts the contact portion 230 of the contact link member200, the contact surface 43 keeps on contacting the contact portion 230in the whole rotation range of the contact link member 200. With thisconfiguration, the rotation of the contact link member 200 is guided, ina sense, by the pressure-receiving member 40, so that the contact linkmember 200 can be operated smoothly.

Further, in this embodiment, since the contact portion 230 and thepressure-receiving member 40 are made of plastic resin, rubbing noisegenerated between the contact link member 200 and the pressure-receivingmember 40 and the abrasion thereof can be suppressed. Further, since thecontact surface 43 has a concavely curved shape and the contact pressurebetween the contact portion 230 and the contact surface 43 is lessened,abrasion of the contact link member 200 and the pressure-receivingmember 40 can be further suppressed.

Next, operations of the driving mechanism 50 and the pressure-receivingmember 40 in a rear-end collision will be described. Herein, the term“in the rear-end collision” indicates an occasion when the car isrear-ended by another car or when the car collides at the rear portionthereof with another car or a structural object while reversing.

As seen in FIG. 15 (a), in a normal condition in which thepressure-receiving member 40 is in the initial position withoutoccurrence of a rear-end collision (i.e., when a load smaller than thepredetermined amount has been input from an occupant to thepressure-receiving member 40), a rearward rotation of the contact linkmember 200 is restricted by the upper connecting wire W1 and the like,so that the pressure-receiving member 40 does not move rearward so muchfrom the initial position.

On the other hand, when a rear-end collision occurs and a load equal toor greater than the predetermined amount is input from the occupant tothe pressure-receiving member 40, this large load causes thepressure-receiving member 40 to move backward, so that the end portionsof the upper connecting wire W1 pull the contact link members 200(connecting portions C3) backward. In so doing, as seen in FIG. 15 (b),the contact link members 200 move rearward while causing the upperconnecting wire W1 and the pressure-receiving member 40 to elasticallydeform laterally inward, so that the pressure-receiving member 40 movesfurther backward from the initial position to the backward positionshown in FIG. 15 (c). When the pressure-receiving member 40 moves to thebackward position, the stopper 210 of the contact link member 200 comesinto contact with the side surface 102 of the drive link member 100, sothat the rotation of the contact link member 200 is restricted and thebackward movement of the pressure-receiving member 40 is restricted aswell.

As seen in FIGS. 16 (a) to (c), when the pressure-receiving member 40moves from the initial position to the backward position, the upper bodyof the occupant sinks into the seat back S2. This makes it possible toallow the head of the occupant to quickly approach the headrest S3 andto be received by the headrest S3, so that an impact imparted to theneck of the occupant in the rear-end collision can be reduced.

In this embodiment, since the contact link member 200 includes thestopper 210, an excessive rearward rotation of the contact link member200 can be prevented. This configuration makes it possible, for example,to adjust the amount of sinking of an occupant into the seat back S2 andto easily return the pressure-receiving member 40 once located in thebackward position to the initial position.

As seen in FIG. 15 (c), the connecting portion C3 is located rearward ofthe rotation center C2 of the contact link member 200 when thepressure-receiving member 40 is in the backward position. In thisposition, the upper connecting wire W1 functions as an urging member forurging the contact link member 200 in the direction shown by the arrow,more specifically, an urging member (second urging member) configured tourge the contact link member 200 to rotate rearward. With thisconfiguration, the pressure-receiving member 40 having been moved intothe backward position due to the rear-end collision can be held in thebackward position, which can suppress undesired forward displacement ofthe pressure-receiving member 40 in reaction to the rearward movementthereof.

Further, in this embodiment, the pressure-receiving member 40 does notcontact the driving source 52 while moving from the initial position tothe backward position and from the initial position to the advancedposition. This configuration can suppress abnormal noise generated bythe movement of the pressure-receiving member 40.

According to the car seat S configured as described above, the drivingmechanism 50 can provide a function of appropriately supporting anoccupant by changing the orientation of the pressure-receiving member 40during cornering as well as a function of reducing an impact imparted tothe occupant by moving the pressure-receiving member 40 to the backwardposition in a rear-end collision. This makes it unnecessary to providewithin the seat back S2 both the mechanism for changing the orientationof the pressure-receiving member and the mechanism for allowing arearward movement of the pressure-receiving member, so that space withinthe seat back S2 is ensured to arrange other mechanisms or the car seatS can be downsized; it is therefore possible to improve the degree offreedom in the design of the car seat S.

Further, providing the upper connecting wire W1 and the torsion spring55 as an example of a rotation resistive member resisting a rearwardrotation of the contact link member 200 can suppress undesired rearwarddisplacement of the pressure-receiving member 40 in the normalcondition.

Further, since the connecting portion C3 is located inside the circle Cwhen the pressure-receiving member 40 is in the initial position, theamount of deformation of the upper connecting wire W1 caused when thepressure-receiving member 40 moves into the backward position can bereduced and upsizing of the upper-connecting wire W1 can be suppressed.

The distal end of the contact link member 200 has the contact portion230 having a convexly curved shape as viewed from a direction of itsaxis of rotation. This configuration makes it possible to lessen thesliding resistance between the contact portion 230 and thepressure-receiving member in the rotating direction of the contact linkmember 200, so that the contact link member 200 and thepressure-receiving member 40 can be moved smoothly during cornering orin a rear-end collision. Further, the contact portion 230 has a convexlycurved shape also as viewed from a direction orthogonal to the directionof the axis of rotation. This configuration makes it possible to lessenthe sliding resistance also in the direction of the axis of rotation ofthe contact link member 200, so that for example, when thepressure-receiving member 40 moves upward or downward, thepressure-receiving member 40 and the like can be moved smoothly.Furthermore, the contact portion 230 has a generally spherical shape, sothat the sliding resistance can be lessen in all directions thereof andwhen the contact link member 200 and the pressure-receiving member 40are operated to contact together, the contact link member 200 and thelike can be moved smoothly.

The upper connecting wire W1 is inserted into the through-hole 240 andconnected to the contact link member 200, so that the contact linkmember 200 and the upper connecting wire W1 can easily be connectedtogether.

As seen in FIG. 11, the drive link member 100 has the stopper portion130, and the stopper portion 130 comes into contact with the fixedstopper member 70 to restrict a rotation of the drive link member 100,so that the amount of rotation of the drive link member 100 can beprecisely regulated as compared with the configuration in which theamount of rotation of the drive link member is regulated, for example,by actuating and stopping a stepping motor. Further, as compared withthe configuration using the stepping motor, the amount of rotation ofthe drive link member 100 can be precisely regulated with a simple andlow-cost structure. Further, since the stopper portion 130 has the firststopper portion 131 and the second stopper portion 132, the amount ofrotation of the drive link member 100 can be precisely regulated bothwhen the drive link member 100 rotates in one direction and when rotatesin the opposite direction.

The driving mechanism 50 (drive link member 100) and the fixed stoppermember 70 are both fixed to the bracket 60, so that the positionalprecision between the stopper member 130 and the fixed stopper member 70can be improved and the amount of rotation of the drive link member 100can be more precisely regulated.

The fixed stopper member 70 is disposed between the output shaft 52C andthe side frame 20, so that upsizing of the drive link member 100 and thefixed stopper member 70 can be suppressed and the structure around thedrive link member 100, more specifically, the structure for restrictingthe rotation of the drive link member 100 can be compact. It is to benoted that downsizing of the drive link member 100 and the structure forrestricting the rotation makes it possible to shorten the length of theprotruding stopper portion 130, so that a load to be generated when thestopper portion 130 contacts the fixed stopper member 70 can be reduced

The stopper portion 130 is provided on the side surface 102 of the drivelink member 100, so that the structure of the drive link member 100 canbe simplified as compared with an alternative configuration in which thestopper portion protrudes from the link member in a direction of theaxis of rotation. Further, the first arm portion 55B of the torsionspring 55 is hooked onto the first stopper portion 131, so that thestructure of the drive link member 100 can be simplified as comparedwith an alternative configuration in which the torsion spring is hookedon another portion (i.e., a portion on which the torsion spring ishooked is provided other than the stopper portion. These configurationsmake it possible to easily manufacture the drive link member 100.

As seen in FIG. 8 (b), the fastening portions 330 protrude from thegearbox 52B and the side surfaces of the gearbox 52B except for thefastening portions 330 have recessed shapes with respect to thefastening portions 330, so that the driving source 52 with the gearbox52B can be compactly formed. Further, the protruding fastening portions330 are arranged at positions avoiding the line LN, so that the sidesurfaces of the gearbox 52B except for the fastening portions 330 andthe end portions of the bent portions 21A of the side frame 20 can bearranged closer to each other. This can suppress upsizing of the sideframe 20 and the like and the structure around the driving source 52 canbe downsized. Further, one fastening portion 330 is arranged on alaterally outer side of the line LN while two fastening portions 330 arearranged on a laterally inner side of the line LN, so that even in thecase where a plurality of fastening portions 330 are provided, the sidesurfaces of the gearbox 52B and the end portions of the bent portions21A can be arranged closer to each other. This makes it possible toprovide a compact structure around the driving source 52.

Although one embodiment of the present invention has been describedabove, the present invention is not limited to the above-describedembodiment. It is to be understood that modifications and changes may bemade to any of the specific configurations as below where necessarywithout departing from the gist of the present invention.

In the above embodiment, the stopper 210 configured to restrict theamount of rotation of the contact link member 200 is provided on thecontact link member 200 itself. However, the present invention is notlimited to this configuration, and the stopper may be provided on thedrive link member, the bracket, the side frame or the like.

In the above embodiment, the contact link member 200 is provided suchthat the cover member 202 entirely covers the link body 201. However,the present invention is not limited to this configuration. For example,as seen in FIG. 17, the cover member 202 may partly cover the link body201. To give more details, the contact link member 200 shown in FIG. 17includes the metallic link body 201 whose one end portion is coveredwith the plastic cover member 202 having the contact portion 230. Inthis structure, the through-hole 240 pierces through the link body 201and the cover member 202, and the upper connecting wire W1 is insertedinto the through-hole 240 so as to prevent the cover member 202 fromcoming off. Further, in the contact link member 200 shown in FIG. 17,the minimum diameter of the through-hole 242 of the cover member 202 issmaller than that of the through-hole 241 of the link body 201. In thisconfiguration, the upper connecting wire W1 inserted into thethrough-hole 240 is brought into contact with the inner peripheralsurface of the through-hole 242 of the plastic cover member 202, so thatcontact noise generated between the contact link member 200 and theupper connecting wire W1 can be suppressed.

In the above embodiment, the contact link member 200 includes the linkbody 201 and the cover member 202, and the link body 201 and the covermember 202 are made of different materials. However, the presentinvention is not limited to this configuration. For example, the entirecontact link member may be made of plastic resin. It is however notedthat if the contact link member 200 includes the link body 201 and thecover member 202 having the contact portion 230 as with the aboveembodiment, each of the link member 201 and the cover 202 can be made ofan optimum material in terms of its function. For example, as with theabove embodiment, if the link body 201 is made of metal and the covermember 202 is made of plastic resin, rubbing noise generated between thecontact link member 200 and the pressure-receiving member 40 can besuppressed and the abrasion can be suppressed while ensuring therigidity of the entire contact link member 200.

In the above embodiment, the contact portion 230 is approximatelyspherical in shape. However, the present invention is not limited tothis specific configuration. For example, the contact portion may have aconvexly curved shape only when viewing from a direction of the axis ofrotation of the link member. Further, the sectional shape of the contactportion is not limited to a circular shape (circular arc shape), and mayhave an elliptic or oval shape.

In the above embodiment, the stopper portion 130 of the drive linkmember 100 contacts the fixed stopper member 70 fixed to the side frame20 to restrict a rotation of the drive link member 100. However, thepresent invention is not limited to this specific configuration. Forexample, the stopper portion may directly contact the side frame torestrict a rotation of the link member.

In the above embodiment, the stopper portion 130 is provided on the sidesurface 102 of the drive link member 100. However, the present inventionis not limited to this specific configuration. For example, the stopperportion may be provided to protrude from the drive link member in adirection of the axis of rotation of the drive link member. Further, inthe above embodiment, the stopper portion 130 includes the first stopperportion 131 and the second stopper portion 132. However, the presentinvention is not limited to this specific configuration. For example,only one stopper portion may be provided. Further, in the aboveembodiment, the right-side drive link member 100 and the left-side drivelink member 100 are provided using a common part. However, the presentinvention is not limited to this specific configuration, and theright-side drive link member 100 and the left-side drive link member 100may be provided using dedicated parts, respectively.

In the above embodiment, the fixed stopper member 70 is fixed to thebracket 60. However, the present invention is not limited to thisspecific configuration. For example, the fixed stopper member may bedirectly fixed to the side frame. Further, in the above embodiment, theentire rotation-restricting portion 73 is made of plastic resin.However, the present invention is not limited to this specificconfiguration. For example, the rotation-restricting portion may beconfigured such that only the surface thereof to which the stopperportion of the drive link member comes into contact is made of plasticresin. With this configuration as well, contact noise generated betweenthe stopper portion and the rotation-restricting portion can besuppressed, so that noise produced by the actuation of the drive linkmember can be suppressed.

In the above embodiment, the coil portion 55A of the torsion spring 55and the upper connecting wire W1 are spaced apart from each other, sothat when the pressure-receiving member 40 moves backward, undesiredengagement of the upper connecting wire W1 with the coil portion 55A canbe suppressed. However, as seen in FIGS. 18 (a) and (b), a cover member400 may be provided between the coil portion 55A and the upperconnecting wire W1.

The cover member 400 is a member configured to partly cover the coilportion 55A of the torsion spring 55, and made of plastic resin, forinstance. The cover member 400 includes a cover portion 410 configuredto cover the outer peripheral surface of the coil portion 55A, an upperengagement portion 420 provided above the coil portion 55A and extendingfrom an upper end of the cover portion 410 to be placed on the pin 54,and a lower engagement portion 430 configured to extend from a lower endof the cover member 410 so as to detour around the contact link member200 into the lower side of the contact link member 200 to engage withthe contact link member 200.

When the contact link member 200 is in the initial position, the covermember 410 extends along the outer peripheral surface of the coilportion 55A from a position at which the cover member 410 covers thatportion of the coil portion 55A which is the nearest to the upperconnecting wire W1 to a position at which the cover member 410 coversthe rear portion of the coil portion 55A, so that the cover member 410is located between the coil portion 55A and the upper connecting wireW1.

The upper engagement portion 420 has an engagement protrusion 421protruding from a lower surface thereof. The engagement protrusion 421engages an engagement recess portion 54A formed on the upper surface ofthe pin 54, so that the upper engagement portion 420 engages the pin 54.

With the provision of the cover member 400 configured as describedabove, when the pressure-receiving member 40 moves backward and theupper connecting wire W1 is caused to move backward to a large extent,the upper connecting wire W1 comes into contact with the cover member410 without contacting the coil portion 55A. This can minimize undesiredengagement of the upper connecting wire W1 with the coil portion 55A.Further, the cover member 400 is made of plastic resin in this modifiedembodiment, so that noise generated when the upper connecting wire W1contacts the cover member 410 can be suppressed.

In the above embodiment, the pressure-receiving member 40 does notcontact the driving source 52. However, the vehicle seat may beconfigured such that the pressure-receiving member 40 contacts thedriving source 52. For example, the lowermost second bead B2 among thesecond beads B2 provided on the pressure-receiving member is disposedsubstantially at the same height position as that of the upper endportion of the driving source 52, and this second bead B2 may contactthe driving source 52 in the initial position.

In the above embodiment, when in the advanced position, the contactpoint P of the contact link member 200 and the pressure-receiving member40 is located frontward farther than the front end of the side frame 20.However, as seen in FIG. 19, even in the initial position, the contactpoint P of the contact link member 200 and the pressure-receiving member40 may be located frontward farther than the front end of the side frame20. In other words, the contact point P of the contact link member 200and the pressure-receiving member 40 may always be located frontwardfarther than the front end of the side frame 20.

In the above embodiment, the contact portion 230 of the contact linkmember 200 is configured to contact the pressure-receiving member 40.However, as seen in FIG. 20, the contact link member 200 may be providedso as not to contact the pressure-receiving member 40.

To be more specific, the upper connecting wire W1 extends along thepressure-receiving member 40 while contacting the first support portion45 of the pressure-receiving member 40 and the second support portion 46of the pressure-receiving member 40 that is provided laterally outwardof the first support portion 45; the upper connecting wire W1 is bentand extends frontward from a portion thereof contacting the firstsupport portion 45 along the second support portion 46. The upperconnecting wire W1 is then bent such that each right and left endportion extends away from the second support portion 46, and connectedto the contact link member 200. The contact link member 200 does notcontact the pressure-receiving member 40 when it moves from the initialposition to the advanced position.

It is preferable that the both right and left ends of the upperconnecting wire W1 extend along the second support portions 46, and morepreferably, the right and left ends of the upper connecting wire W1extend outward along the second support portions 46 beyond the laterallymidpoint of each of the second support portions 46 in order to push thepressure-receiving member 40 at positions closer to its laterally outerportions by the upper connecting wire W1. With this configuration, thepressure-receiving member 40 can be stably supported by the upperconnecting wire W1.

In the above embodiment, the coil portion 55A of the torsion spring 55is disposed on the opposite side of the contact link member 200 from thedriving source 52, and as viewed from the upper-lower direction, thecoil portion 55A is disposed to overlap the driving source 52. However,the arrangement of the driving source and the torsion spring is notlimited to this specific arrangement. For example, as seen in FIG. 21,the coil portion 55A of the torsion spring 55 may be disposed on thesame side of the contact link member 200 as that on which the drivingsource 52 is disposed so that the coil portion 55A and the drivingsource 52 overlap each other in the horizontal direction. Thisconfiguration makes it possible to reduce the size of the drivingmechanism 50 in the upper-lower direction.

As seen in FIG. 22 (a), the pressure-receiving member 40 may have cutportions 47 at portions corresponding to the shoulders of an occupant,i.e., at right and left upper end portions. To be more specific, theupper end of each of the support portions 42 is provided at a positionone step lower than the upper end of the pressure-receiving member 41.An occupant may look back, while driving a car in reverse, and take aposture with his/her one shoulder directed rearward. In so doing, if thecut portions 47 are not provided on the pressure-receiving member 40, anoccupant may find difficulty in looking back because when thepressure-receiving member 40 moves in a direction opposite to theoccupant's posture due to the steering maneuver of the occupant, theadvanced support portion 42 contacts the occupant's shoulder.

Further, as seen in FIGS. 22 (a) and (b), the pressure-receiving member40 may be easily bendable at its laterally center portion. To be morespecific, the pressure-receiving member 40 has bend lines extending inthe upper-lower direction (e.g., groove 48 recessed as viewed from thefront side) at the laterally center portion thereof, and this portionwith the grooves 48 is thinner than other portions. Thispressure-receiving member 40 is bent at the groove 48 when the supportportion 42 of the pressure-receiving member 40 is pushed forward by thedriving mechanism 50, so that the right-side support portion 42 and theleft-side support portion 42 are independently movable. It is to benoted that the groove 48 may be recessed as viewed from the rear side,or both the front side and the rear side thereof may be recessed. Thebend line is not limited to the groove, and a perforated line extendingin the upper-lower direction may be provided at the laterally centerportion of the pressure-receiving member 40.

Further, the pressure-receiving member 40 may be divided into right andleft halves by the center portion thereof. For example, as seen in FIG.23, the pressure-receiving member 40 may consist of two plate members401 arranged side by side. The two plate members 401 may be connected attheir lower end portions. According to these pressure-receiving members40, the right-side support portion 42 and the left-side support portion42 can be moved more independently.

In the above embodiment, the bent portion W11 of the upper connectingwire W1 is of U-shape. However, as seen in FIG. 24 (b), the bent portionW11 may be of V-shape with the lower end portion thereof disposed in thelaterally center portion of the third portion 40C. With thisconfiguration, the upper connecting wire W1 can push thepressure-receiving member 40 at the narrowed portion as well, so thatthe pressure-receiving member 40 is easily twistable at the thirdportion 40C. Further, since the upper connecting wire W1 supports notonly the second portion 40B but also the third portion 40C from the rearside, an occupant can be stably supported by the pressure-receivingmember 40.

In the above embodiment, the upper frame 10 is fixed to the side framemain body portions 21. However, the configuration of the seat back frameF2 is not limited to this specific configuration. For example, as seenin FIG. 24 (a), the upper frame 10 may be supported by the side framemain body portions 21 so as to be rotatable frontward and rearwardrelative thereto.

To be more specific, the upper frame 10 includes a pair of right andleft upper side frames 13A rotatably connected to the side frame mainbody portions 21. Further, as seen in FIG. 24 (b), the upper frame 10includes a cross-member 14 configured to connect the pair of upper sideframes 13A.

The pressure-receiving member 40 is supported by this seat back frame F2such that the first portion 40A and the second portion 40B are supportedby the side frame main body portions 21 with both the driving mechanisms50 and the lower connecting wire W2 being fixed to the side frame mainbody portions 21. With this configuration, the pressure-receiving member40 does not move by the rotation of the upper frame 10, so that anuncomfortable feeling experienced by an occupant can be suppressed.

Each driving mechanism 50 as a whole is disposed below the axis ofrotation 20A on which the upper frame 10 is rotatable with respect tothe side frame main body portions 21. This can prevent the drivingsources 52 and other parts constituting the driving mechanisms 50 fromprotruding rearward to a large extent from the seat back frame F2 whenthe upper frame 10 rotates frontward.

Further, the upper end of the pressure-receiving member 40 is disposedbelow the cross-member 14, more specifically, the axis of rotation 20Aon which the upper frame 10 is rotatable with respect to the side framemain body portions 21. This can prevent the upper end portion of thepressure-receiving member 40 from protruding rearward to a large extentfrom the seat back frame F2 when the upper frame 10 rotates frontward.Further, since the cross-member 14 is disposed above thepressure-receiving member 40, the upper body of an occupant is apt tosink into the seat back S2 in a rear-end collision.

As seen in FIG. 25, in the case where the seat back frame F2 isconfigured to be rotatable around the axis of rotation 25A provided at alower portion thereof, the pressure-receiving member 40 may be providedsuch that the first portion 40A thereof is disposed below the axis ofrotation 25A and the second portion 40B thereof is disposed above theaxis of rotation 25A.

To be more specific, the seat back frame F2 includes right and leftlower side frames 25 each having an upper end portion to which the lowerend of the corresponding side frame main body portion 21 is rotatablyconnected. The driving sources 52 are fixed to the side frame main bodyportions 21, and the lower connecting wire W2 is fixed to the lower sideframes 25. In other words, the first portion 40A of thepressure-receiving member 40 is supported by the lower side frames 25,and the second portion 40B of the pressure-receiving member 40 issupported by the side frame main body portions 21.

The third portion 40C of the pressure-receiving member 40 is providedsubstantially at the same height as that of the axis of rotation 25A ofthe seat back frame F2, and a bend line is formed by which the secondportion 40B is easily swingable frontward and rearward relative to thefirst portion 40A. The bend line may be a groove, perforated line orbellows as shown in FIG. 25. With this configuration, when the sideframe main body portions 21 are tilted frontward around the axis ofrotation 25A, the second portion 40B moves frontward in accordance withthe movement of the side frame main body portions 21, so that anuncomfortable feeling experienced by an occupant can be suppressed.

Further, the third portion 40C may be configured to be stretchable inthe upper-lower direction so that the second portion 40B can easily movein accordance with the movement of the side frame main body portions 21if the third portion 40C is located in a position shifted frontward orrearward with respect to the axis of rotation 25A. In this example, thethird portion 40C may be folded into bellows for instance.

In the above embodiment, each of the side frame main body portions 21 ismade of a single unitary part. However, the structure of the side framemain body portion 21 is not limited to this specific one, and as seen inFIG. 26, the side frame main body portion 21 may be made of upper andlower plates (two plates).

To be more specific, the side frame main body portion 21 consists of anupper frame 211 and a lower frame 212 disposed under the upper frame211. The upper frame 211 and the lower frame 212 are fixed to each otherby welding, a screw or other means.

The second bracket 62 for supporting the driving source 52 is providedto overlap a boundary defined between the upper frame 211 and the lowerframe 212. The fixing portion 62B of the second bracket 62 includes anupper fixing portion 62D fixed to the upper frame 211 by a bolt, and alower fixing portion 62E extending downward from the upper fixingportion 62D and fixed to the lower frame 212 by a bolt. The upper frame211 and the lower frame 212 can be fixed more firmly by this secondbracket 62.

In the case where the side frame main body portion 21 consists of thehorizontally divided upper frame 211 and lower frame 212 as seen in FIG.26, the first bracket 61 and the second bracket 62 may be arranged atpositions avoiding a connecting portion by which the upper frame 211 andthe lower frame 212 are connected, namely, the boundary between theupper frame 211 and the lower frame 212.

As seen in FIGS. 27 (a) and (b), in the case where an air bag device Ais attached to a laterally outer side of the side frame main bodyportion 21, an attachment hole 21B for webbing A1, through which thewebbing A1 configured to restrict a direction of deployment of a bagmember of the air bag device A is attached to the side frame main bodyportion 21, may be provided at a position not overlapping the firstbracket 61 (see FIG. 5) or the second bracket 62. To be more specific,the attachment hole 21B is provided at a position laterally overlappingthe motor 52A that is thinner in width than other portions of thedriving source 52, such as the gearbox 52B. Further, the attachment hole21B is provided at a position not overlapping in the lateral direction(i.e., at a position shifted in the vertical direction from) the contactlink member 200 or the fixed stopper member 70.

Herein, the structure around the air bag device A in the seat back S2will be briefly described. The air bag device A includes various partssuch as a bag member (not shown) and an inflator (not shown), and isfixed to the side frame main body portion 21 via a support plate A3. Theair bag device A is disposed at a position laterally overlapping thedriving source 52.

The webbing A1 is disposed to surround the air bag device A; a front endportion of the webbing A1 and an outer skin material BP5 are sewedtogether at a tear-off portion BP51 of the outer skin material BP5, anda rear end portion of the webbing A1 is fixed to the side frame mainbody portion 21. When the air bag device A is actuated, the bag memberthat is being expanded using a gas generated by the inflator is guidedto expand frontward by the right and left webbing A1, breaks the outerskin material BP5 at the tear-off portion BP51, and deploys at a side ofan occupant

Rear end portions of the webbing A1 are fixed to rivet-like webbingattachment members A2. One of the webbing attachment members A2 isengaged with the attachment hole 21B and fixed to the side frame mainbody portion 21. The other one of the webbing attachment members A2 isengaged with the rear-side bent portion 21A of the side frame main bodyportion 21 and fixed to the side frame main body portion 21.

According to this modified embodiment, since the attachment hole 21B isprovided in such a position that it does not overlap the first bracket61 or the second bracket 62, interference between the webbing attachmentmember A2 engaged in the attachment hole 21B and the brackets 61, 62 canbe suppressed. Further, since the attachment hole 21B is provided insuch a position that it laterally overlaps the motor 52A, the size ofthe side frame main body portion 21 can be reduced as compared with analternative configuration in which the attachment hole 21B is providedin such a position that it does not overlap the motor 52A (drivingsource 52). Further, since the motor 52A is a portion thinner than otherportions of the driving source 52, interference between the webbingattachment member A2 and the driving source 52 can be suppressed.Furthermore, since the webbing attachment member A2 is disposed in sucha position that it does not overlap in the lateral direction the drivelink member 100, the contact link member 200, or the fixed stoppermember 70, the lateral size of the seat back S2 can be reduced ascompared with an alternative configuration in which any of the linkmembers 100, 200 and the fixed stopper member 70 is provided at the sameheight as that of the webbing attachment member A2. Further, since theair bag device A is disposed in such a position that it overlaps in thelateral direction the driving source 52, the size of the side frame mainbody portion 21 can be reduced in the upper-lower direction.

A further attachment hole 21B may be provided at a position above thedriving source 52, and the rear end portions of the webbing A1 may befixed to the side frame main body portion 21 at upper and lower portions(two portions) of the side frame main body portion 21. In thismodification, the driving source 52 is disposed between the twoattachment holes 21B, so that the size of the side frame main bodyportion 21 can be reduced in the front-rear direction as well as in theupper-lower direction. The air bag device A may be arranged so as not tooverlap in the lateral direction the driving source 52, namely, at aposition shifted in the front-rear direction from the driving source 52.In this modification, since the driving source 52 and the webbingattachment member A2 do not overlap each other in the lateral direction,the size of the seat bag S2 can be reduced in the lateral direction.

In the above embodiment, the torsion spring 55 is exemplified as anexample of an urging member. However, the present invention is notlimited to this specific configuration. For example, a leaf spring maybe used instead. Further, in the above embodiment, the upper connectingwire W1 is exemplified as an example of a second urging member. However,the present invention is not limited to this specific configuration. Forexample, a coil spring may be used instead. In the above embodiment, theupper connecting wire W1 and the torsion spring 55 are exemplified as anexample of a rotation resistive member. However, the present inventionis not limited to this specific configuration. For example, the urgingmember, the second urging member, and the rotation resistive member maybe made of independent and discrete members, respectively.

In the above embodiment, a part of the extension portion 62C of thesecond bracket 62 fixed to the side frame 20 is disposed on the bulgingportion 22 of the side frame 20. However, the present invention is notlimited to this specific configuration. For example, the extensionportion as a whole may be disposed on the bulging portion 22.

The structure of the bracket 60 shown in the above embodiment has beenexplained by way of example only. For example, although the fixingportion 62B of the second bracket 62 has the extension portion 62C, thepresent invention is not limited to this specific configuration, and thefixing portion of the first bracket may have an extension portion.Further, referring to FIG. 8 (a) for a reference purpose, the engagementportion 62A of the second bracket 62 may engage the lower end portion ofthe driving source 52, and the fixing portion 62B may extend down to aposition lower than the lower end of the driving source 52. Further, inthe above embodiment, the bracket 60 includes two brackets, namely, thefirst bracket 61 and the second bracket 62. However, the presentinvention is not limited to this specific configuration, and the bracketmay consist of one bracket.

In the above embodiment, the linkage 51 includes two links (the drivelink member 100 and the contact link member 200). However, the presentinvention is not limited to this specific configuration. For example,the linkage may include one link member, or alternatively three or morelink members.

The above embodiments have been illustrated as examples in which thepresent invention is applied to a seat used in an automobile (i.e., carseat S). However, the present invention is not limited thereto, andapplicable to any other seat used in other vehicles, such as rail cars,ships and aircraft.

The invention claimed is:
 1. A vehicle seat with a seat cushion and aseat back, the vehicle seat comprising: right and left side framesconstituting right and left frames of the seat back; apressure-receiving member disposed between the right and left sideframes and configured to receive a load from an occupant; and a drivingmechanism disposed at each of right and left sides of thepressure-receiving member and configured to cause a right end portion ora left end portion of the pressure-receiving member to move from aninitial position to an advanced position that is located frontward ofthe initial position or to move from the advanced position to theinitial position, wherein the driving mechanism comprises a linkageconfigured to be connected to the pressure-receiving member and adriving source configured to actuate the linkage, wherein the linkageincludes a link member configured to be rotatable frontward and rearwardrelative to the side frame and connected to the pressure-receivingmember, and is configured to operate when a load equal to or greaterthan a predetermined amount is input from the occupant to thepressure-receiving member to cause the pressure-receiving member to moveto a backward position that is located rearward of the initial position,wherein the vehicle seat comprises a rotation resistive memberconfigured to restrict a rearward rotation of the link member when aload smaller than the predetermined amount is input from the occupant tothe pressure-receiving member and to deform when a load equal to orgreater than the predetermined amount is input from the occupant to thepressure-receiving member so as to allow a rearward rotation of the linkmember, and wherein the rotation resistive member comprises an urgingmember configured to urge the link member to rotate frontward.
 2. Thevehicle seat according to claim 1, wherein the rotation resistive membercomprises a connecting wire configured to connect the pressure-receivingmember and the link member.
 3. The vehicle seat according to claim 1,wherein the linkage includes a second link member connected to an outputshaft of the driving source, and wherein the link member is rotatablerelative to the second link member.
 4. The vehicle seat according toclaim 1, wherein the link member has a contact portion configured tocontact the pressure-receiving member when the pressure-receiving memberis caused to move, and wherein as viewed from a direction of an axis ofrotation of the link member, the contact portion has a convexly curvedshape.
 5. The vehicle seat according to claim 4, wherein as viewed froma direction orthogonal to the direction of the axis of rotation, thecontact portion has a convexly curved shape.
 6. The vehicle seataccording to claim 4, wherein the contact portion has a spherical shape.7. The vehicle seat according to claim 4, wherein the contact portion ismade of plastic resin.
 8. The vehicle seat according to claim 4, whereinthe link member comprises a link body, and a cover member provided withthe contact portion and configured to cover at least a part of the linkbody.
 9. The vehicle seat according to claim 1, wherein the linkage is aright-side linkage, wherein the driving mechanism further comprises aleft-side linkage configured to be connected to the pressure-receivingmember, the right-side linkage includes a right-side second link memberconfigured to be rotatable relative to the side frame and to actuate thepressure-receiving member, the left-side linkage includes a left-sidesecond link member configured to be rotatable relative to the side frameand to actuate the pressure-receiving member, wherein the driving sourceis configured to rotate the right-side second link member and theleft-side second link member, wherein at least one of the right-sidesecond link member and the left-side second link member has a stopperportion configured to contact a corresponding side frame or a memberfixed relative to the corresponding side frame to restrict a rotation ofthe at least one of the right-side second link member and the left-sidesecond link member, and wherein the right-side second link member andthe left-side second link member are independently rotatable to eachother.
 10. The vehicle seat according to claim 9, wherein the stopperportion comprises a first stopper portion configured to restrict arotation of at least one of the right-side second link member and theleft-side second link member in one direction and a second stopperportion configured to restrict a rotation of at least one of theright-side second link member and the left-side second link member in adirection opposite to the one direction.
 11. The vehicle seat accordingto claim 9, wherein the right-side second link member and the left-sidesecond link member are each formed from a part which is structurally thesame.
 12. The vehicle seat according to claim 9, wherein at least one ofthe right-side second link member and the left-side second link memberis shaped as a plate, and wherein the stopper portion is provided on aside surface surrounding an axis of rotation of at least one of theright-side second link member and the left-side second link member. 13.The vehicle seat according to claim 9, further comprising: a bracketwith which the driving mechanism is fixed to the side frame; and a fixedstopper member fixed relative to the side frame and configured such thata rotation of at least one of the right-side second link member and theleft-side second link member is restricted when the stopper portioncontacts the fixed stopper member, wherein the fixed stopper member isfixed to the bracket.
 14. The vehicle seat according to claim 1, whereinthe side frame has a pair of inwardly bent portions at both sideportions of the side frame, each located at an end in a width direction,wherein the driving source comprises a motor, a gearbox configured toaccommodate a train of gears for reducing speed with which istransmitted a rotary driving force generated by the motor, and an outputshaft configured to output the rotary driving force transmitted with thereduced speed, wherein the gearbox has a fastening portion protrudingradially outward of the output shaft such that a fastening member forclosing an axial end portion of the output shaft is disposed in thefastening portion, and wherein as viewed from an axial direction of theoutput shaft, the fastening portion is arranged at a position avoiding astraight line connecting ends of the pair of bent portions.
 15. Thevehicle seat according to claim 14, wherein as viewed from the axialdirection, the fastening portion is provided at a plurality ofpositions, at least one on each side of the straight line.
 16. Thevehicle seat according to claim 14, further comprising a bracket withwhich the driving source is fixed to the side frame, wherein the bracketcomprises an engagement portion engageable with one end portion of thedriving source located at one end thereof in the axial direction of thedriving source, and a fixing portion extending along the side frame froman end portion of the engagement portion located closer to the sideframe toward a direction opposite to another end portion of the drivingsource that is located at another end thereof opposite to the one end inthe axial direction of the driving source and fixed to the side frame.17. The vehicle seat according to claim 1, wherein the urging member isa torsion spring hooked onto the link member.
 18. The vehicle seataccording to claim 1, wherein the urging member is hooked onto the linkmember, wherein the rotation resistive member comprises a connectingwire connecting the pressure-receiving member and the link member,wherein a connecting portion connecting the connecting wire and the linkmember is located at a position frontward of a rotation center of thelink member when the pressure-receiving member is in the initialposition, and is located rearward of the rotation center of the linkmember when the pressure-receiving member is in the backward position,and wherein the connecting wire urges the link member to rotate rearwardwhen the pressure-receiving member is in the backward position, andcauses the pressure-receiving member to be held in the backwardposition.
 19. The vehicle seat according to claim 1, wherein the linkageis a right-side linkage, and the link member is a right-side linkmember, wherein the driving mechanism further comprises a left-sidelinkage configured to be connected to the pressure-receiving member, andthe left-side linkage includes a left-side link member configured to berotatable frontward and rearward relative to the side frame andconnected to the pressure-receiving member, wherein when thepressure-receiving member is caused to move from the initial position tothe backward position, both of the right-side link member and theleft-side link member rotate backward.